Internal-combustion engine



2 Sheets-Sheet i J. G. SHEPARD Filed June 9, 1.944

INTERNAL-COMBUSTION ENGINE June 4, 1946.

June 1945- J. G. SHEPARD I INTERNAL- COMBUSTION ENGINE 2 Sheets-Sheet 2Filed June 9, 1944 In/n/Ol" Patented June 4, 1946 UNITED STATES PATENTOFFICE INTERNAL-COMBUSTION ENGINE James G. Shepard, Toronto, Ontario,Canada Application June 9, 1944, Serial No. 539,518 Claims. (01. 123-50) The present invention relates to improvements in internalcombustion engines of the two-stroke cycle type and the principal objectof the invention is to eifectively increase the efficiency of the enginewhile reducing the stresses upon the cylinder and pistons by applyingthe force of the explosions in opposite directions to develop a balancedtorque in the crank shaft.

A further object of the invention is to ensure a uniform vaporization offuel and carburetion of air entering the cylinder at all speeds.

The principal feature of the invention consists in the novelconstruction and arrangement of parts whereby a piston operativelyconnected to a crank of the crank shaft operates within a reciprocatingcylinder piston operatively connected with cranks of the crank shaftarranged in opposed relation to the aforesaid crank, said cylinderpiston operating within a fixed cylinder having an air intake port and adischarge port leading through a carburetter to an inlet port whichconnects with the combustion chamber.

In the accompanying drawings Figure 1 is a longitudinal mid-sectionalview through an engine and carburetter constructed in accordance withthis invention, the pistons being shown in the firing position at thepoint of highest compression.

Figure 2 is a longitudinal mid-sectional view through the engine showingthe pistons at the limit of the outward or power stroke.

Figure 3 is a cross section through a portion of the carburetter on theline 33 of Figure 1.

Figure 4 is an elevational detail of the carburetter and air tubeleading thereto taken at right angles to the illustration of Figure 1.

Referring to the accompanying drawings, the engine base I has journalledtherein a crank shaft 2 which is formed with a central crank 3 andcranks 4 arranged at either side of and in opposed relation, 180degrees, to the crank 3.

Mounted on the base I is the stationary cylinder 5, the lower portion '6of which is of lesser diameter than the upper portion 1.

Mounted within the cylinder 5 is a reciprocating cylinder 8 whichslidably engages the inner wall of the lower portion 6 thereof and isprovided with an enlarged piston head 9 operating within the upperportion 1 of said cylinder 5, said piston head being provided withsuitable spaced-apart piston rings II).

A radial inlet port I I extends through the wall of the piston head 9between the rings I0 and forms a communicating port between'the upperend of the interior of the cylinder 8 and an inlet port I2 in the wallof the stationary cylinder 5.

Connecting rods I3 are mounted on wrist pins I4 secured to the lower endof the reciprocating cylinder 8 and connect the said cylinder 8 with thepaired cranks 4.

A piston I5 is arranged to reciprocate within the cylinder 8 and isconnected with the crank 3 by a connecting rod I6.

The dimensions of the cylinder 8, piston l5 and their connecting rodsare such that when the centre crank 3 is in its uppermost position andthe cylinder 8 is in the lowermost position, as

shown in Figure 1, the combustion chamber I! will be of the requireddimensions to produce the desired compression of combustion gases, theinlet port II to said cylinder being closed by the cylinder wall 8 andsealed by the piston rings It].

An air inlet port I8 is arranged in the wall of the cylinder 5 in such aposition that it will be uncovered by the piston head 9 when thecylinder 8 is in its lowermost position, allowing air to flow into theinterior of the cylinder 5.

The cylinder 5 is closed by a head I9 which is 5 formed with an aircompression chamber 20.

. 2| in which is mounted a rotatable throttle valve 22 operated by aspindle 23, said valve having openings 24 therein to register withcorresponding openings in a throttle plate 25 mounted in the carburetterpassage 26.

A tube 21 opening into the side wall of the carburetter 2| is providedwith a suitable venturi 2B and a fuel jet 29 to which fuel is fed fromthe float chamber 30, the flow of fuel being regulated by a needle valve3!.

A tube 32 opening from the air compression chamber 20 communicates withthe tube 21 below the venturi and directs air compressed in said chamberaround the fuel jet into the venturi. The air, being under compressionefiected by the upward movement of the piston head 9 of the cylinder 8,flows with uniform velocity through the carburetter upon the opening ofthe inlet port I I into the cylinder 8.

An exhaust port 33 is arranged in the side wall of the cylinder 5 and aport 34 is arranged in the cylinder 3 to register therewith, both portsbeing uncovered by the piston I5 as it approaches the lower end of itsstroke to permit the escape of the products of combustion, such escapebeing assisted by the inflow of a-charge of carburetted air through theinlet port II in the cylinder 8 which opens the *nlet I2 from thecarburetter nected with the high tension terminal 40 arranged in a cap4|.

It will be understood that upon the ignition of the compressed chargewithin the cylinder 8 the expansion of the charge forces the piston I5downwardly and the reciprocating cylinder 8 up- I wardly, thussimultaneously applying a pushing stroke to the crank 3 and a pullingstroke to the cranks 4. The cylinder head moves upwardly while thepiston moves downwardly the fullc'rank stroke, consequently theeffective longitudinal dimension of the combustion chamber is twice thecrank stroke.

Since the stroke of the piston cylinder 8 is only one half the stroke ofthe piston l5 relative to said piston 8 the area of the piston head 9will be twice the area of the piston IS in order that the displacementof both pistons will be equal. At the moment of ignition the compressionchamber is filled with air at atmospheric pressure through the inletport l8, and the upward movement of cylinder head Bioloses theport andcompresses the air in the chamber 20.

At a predetermined point, approximately 30 degrees in advance of deadcentre, the exhaust port 34 and inlet port II in cylinder 8 commence toopen. The products of combustion escape from the bottom of the cylinder8 above the piston 15 and the compressed air from the chamber 20 flowsthrough the tubes 32 and 21 to and through the venturi 28 of thecarburetter into the top end of the cylinder through the ports 12 andII, thus thoroughly scavenging the burnt gases .from the cylinder. Theflow of air from the compression chamber through the venturi 28 createsa uniform and highly vaporized mixture and such flow will be uniform atall speeds of engine operation and ensures the utilization of the fullvolumetricw capacity of the cylinder independent of the speed of thepiston travel, which is in efiect similar to a supercharger.

The movement of the pistons closes the exhaust and intake ports atapproximately 30 degrees past dead centre and the cylinder 8 and pistonI5 then move toward each other in the compression cycle until firingagain takes place and the cycle is repeated.

The double crank action produced by the double piston movement relievesthe bearings of the crank shaft of considerable stress over an enginewhere the thrust is in one direction. Further, the extra length ofcombustion space ensures the maximum power value, and when suchelongated expansion stroke is obtained the firing compression may begreatly lessened and so reduce the cylinder head stresses.

What I claim as my invention is: I

1. In an internal combustion engine, a fixed cylinder, a crank shafthaving oppositely disposed cranks, a cylinder piston operable in theaforesaid cylinder and operatively connected to one of said cranks, apiston'operable within said cylinder piston and operatively connected tothe other of said cranks, a compression chamber arranged at the head ofsaid fixed cylinder and having an inlet port controlled by said cylinderpiston, a carburetter having an inlet port connected with saidcompression chamber and a discharge port opening to the fixed cylinderadjacent to the top, an inlet port in said cylinder piston adjacent tothe top thereof and directing carburetted airto the interior of thecylinder piston at the upper end of its stroke, and an exhaust portcontrolled by said piston cylinder.

2. In an internal combustion engine, a stationary cylinder, areciprocating cylinder mounted in said stationary cylinder, a pistonoperating in said reciprocating cylinder, a crank shaft having acentrally arranged crank and a crank arranged at each side of saidcentral crank and opposed thereto, a connecting rod connecting thecentral crank with said. piston, a pair of connecting rod connectingsaid reciprocating cylinder with the pair of opposed cranks, acompression chamber arranged at the top of said stationary cylinderhaving an inlet through the side wall of the cylinder controlled by thereciprocating cylinder and arranged immediately above the top of saidreciprocating cylinder when said cylinder is at the lower limit of itsstroke, said stationary cylinder having a second inlet port arrangedintermediate of the stroke of the head of the reciprocating cylinder,said reciprocating cylinder having an inlet port adapted to communicatewith the latter inlet port in the stationary cylinder when saidreciprocating cylinder approache the upper limit of its stroke, acarburetter having its discharge connected with the upper inlet port inthe stationary cylinder, a duct connecting said compression chamber withsaid carburetter and compressed air therethrough during the upwardstroke of the reciprocating cylinder, and a po t through the wall of theupper end of said cylinder piston adapted to connect with the port fromthe carburetter at the upper endof the stroke of the reciprocatingcylinder.

3. In an internal combustion engine, a stationary cylinder having theupper portion of its bore of a diameter larger than the lower portion, areciprocable piston cylinder slidably engaging the lower and smallerbore of the stationary cylinder and having an enlarged head slidablyengaging the larger upper bore of the cylinder, spaced-apart pistonrings mounted in the enlarged head of said reciprocating pistoncylinder, an inlet port extending through the wall of the enlarged headof the reciprocating cylinder between said piston rings, an inlet portarranged in the wall of the stationary cylinder adapted to register withthe inlet port in the reciprocating cylinder as said reciprocatingcylinder approaches the outward ends of its stroke, an intake portarranged in the wall of the stationary cylinder and adapted to beuncovered by. said reciprocating piston cylinder as it approaches theend of its downward stroke, a compression chamber arranged at the upperend of the stationarycylinder, a carburetter arran ed to discharge intothe upper inlet port in the stationary cylinder, a duct leading from thecompression chamber to said carburetter to direct compressed airthereto, an exhaust port in the side wall of the stationary cylinder, anexhaust port arranged intermediate of the length of the reciprocatingpiston cylin-,

der adapted to register with the exhaust port in the stationary cylinderand adapted to be uncovered by the piston operating in saidreciprocating piston cylinder 35 said piston approaches the downwardlimit of its stroke, a crank shaft having a central crank operativelyconnected with said piston, and cranks arranged either side of saidcentral crank and opposed thereto and operatively connected with saidreciprocating piston cylinder.

4. In an internal combustion engine, a stationary cylinder having anenlarged bore at its upward end, a reciprocating piston cylinderarranged in said stationary cylinder having an en larged head operatingin the upper enlarged bore thereof, a piston operating in saidreciprocating cylinder, a crank shaft having a central crank and opposedcranks arranged at either side thereof, a connecting rod connecting saidcentral crank with said piston, wrist pins mounted on the lower end ofsaid reciprocating piston cylinder, connecting rods connecting saidwrist pins 20 tionary cylinder having an intake port at the lower endthereof and an inlet port intermediate of the length thereof, an inletport in the enlarged head of the reciprocating piston cylinder adaptedto connect the intermediate inlet port with the combustion chamberbetween the head of the piston cylinder and the piston operatingtherein, a carburetter connected with the inlet port, a port leadingfrom the compression chamber to the carburetter, and means carried bysaid reciprocating piston cylinder for igniting the explosive charge inthe combustion chamber.

5. An internal combustion chamber as claimed in claim 1, having a sparkplug mounted in the head of the reciprocating piston cylinder and havingan extension contact rod extending through the compression chamber,contact means arranged above said compression chamber engaging saidspark plug extension in sliding contact, and sealing means surroundingsaid slidable extension.

JAMES G. SHEPARD.

